This invention relates to a tape wrapped conductor, and to apparatus for producing such tape wrapped conductor.
An electrical conductor is generally assembled by means of a tape wrapped about the conductor. In some cases, more than one conductor is utilized, in which case each of the conductors are individually insulated by an extruded insulation and are then combined by a suitable tape wrapping about the combined conductors. A drain wire may also be placed about the tape wrapped conductors and the composite may then be further covered with an outer protective coating.
One example of this type of electric conductor assembly is described in U.S. Pat. No. 4,041,237 which describes utilizing two insulated wire conductors which are protected with a helically wound tape having an aluminum foil layer facing the conductors and a mylar layer facing outward of the conductors. A drain wire is disposed within the tape against the aluminum layer, and an outer insulation jacket is extruded onto the tape.
Various types of apparatus are available for placing the various insulators on the conductors. For example, in U.S. Pat. No. 3,756,004 there is provided a tape wrapping apparatus where the wire is advanced from a supply to a take up reel. Tape is fed to the advancing wire through pinch rollers which are driven by a speed drive mechanism which is adjusted under control of the advancing wire. The rate of drive of the pinch rollers is coordinated with the tape feed whereby the tape is supplied at a proper rate to the advancing wire.
Although such apparatus may be effective for a single layer of tape, problems arise when overlying layers of tapes are required for the composite conductor cable assembly. It becomes difficult to coordinate and integrate the speed of the tape drive to properly place the desired layer of tape with the proper overlap onto the previous conductor assembly. This problem is further complicated when it is realized that overlying layers of tape become thicker and accordingly the speed of the tape drive must correspondingly be adjusted. The situation is made more difficult when a type of cable assembly is utilized which includes a drain wire since the drain wire is wrapped about the assembly, and accordingly the tape overlying such drain wire cannot be applied with a uniform speed.
Accordingly, there is need for an apparatus which can apply various layers of tape, drain wire, etc. onto conductors in suitable successive steps to achieve a single composite tape wrapped conductor assembly.
Other problems existing with prior art tape wrapped conductors concern the possibility of shorts occurring between the shield and the conductor. Where the tape includes an aluminum foil layer, and the aluminum foil layer is placed adjacent to the conductor, there exists the problem of shield-to-conductor shorts, the lack of pair-to-pair isolation causing the conductor assembly to malfunction.